Combination of Leukocyte Cell Surface Biomarkers Measured by Cytometry, to Differentiate Bacterial From Viral Infections in Emergency Department: a Multicentric Cohort for the Validation of Diagnostic Performances (CYTOBACT)

The characterization of the bacterial or viral etiology of an infectious event is required for both isolation decisions and rationale use of antibiotics. In emergency room (ER), the direct identification of the causal pathogen is rarely available in real-time. Alternative is the identification of the host-response to either a bacterial or viral infection. One of this host-response is the expression of peripheral leukocytes cell surface markers, measured by flow cytometry. Investigators and others have reported the high diagnostic performances of combination of cell surface biomarkers to differentiate bacterial from viral infection. The CYTOBACT study aims to confirm on a 500 patients multicentric cohort (200 having already been collected during another study: SEPTIMET), the best combinations for this diagnostic issue.

The study will be conducted in 3 emergency departments of APHP hospitals network in Paris, France. Patients with a suspicion of infection will be proposed to participate. No intervention will be introduced during the routine care in the (ER) which will be let at the discretion of the treating emergency physician. During the routine blood sampling in the ER, an additional 30 ml volume of whole blood will be collected, centrifugated, aliquoted and stored at -80°C for further measurement of the expression of a panel of cell surface markers. The participants will be followed up during their hospitalization (if any) and no longer than 28 days. Clinical data at admission, usual blood tests and all microbiological investigations performed during the hospital stay will be recorded into an electronic case record form (eCRF). Based on all those recorded data (excepted the results of flow cytometry for cell surface biomarkers) 2 independent adjudicators will qualify the infectious episode into bacterial,viral or no infection, and (if any) into infection, sepsis or septic shock (according to Sepsis 3.0 definitions).

Using different "machine learning" statistical tools, all the combination of the cell surface biomarkers will be tested to select those with the highest performance to differentiate bacterial from viral infection.

Study Overview

• Status: Not yet recruiting
• Conditions: Bacterial and Viral Infections
• Intervention / Treatment: Diagnostic test: 2 additional whole blood samples of 6mL each will be taken

Detailed Description

Patients attending the ED of one of the participant centers for a suspicion of infection will be informed and asked to participate. After obtaining a non-opposition to participate, during the routine blood sampling performed in the ER, an additional volume of 30 ml of whole blood will be collected, aliquoted and stored at -80°C, comprising notably 12 ml of whole blood to which 1 ml of Cytodelics® Stabiliser will be added and incubated à room temperature for 10 mn before being aliquoted and stored at -80°C. The remaining whole blood will be collected on EDTA and Paxgen tubes, centrifugated, aliquoted and stored at -80°C for blood collection.

Clinical data at admission (past medical history, vital parameters, infectious source (if any), treatments delivered in the ER) will be recorded into an eCRF. The participants will be followed up until leaving the hospital and no longer than day-28. All the microbiology tests performed during the hospital stay will be also recorded into eCRF. The diagnostic performance of the combinations of cell surface markers will be evaluated against a diagnostic reference on the bacterial of viral qualification of each infectious event. This diagnostic reference will be established by an independant expert comitee after reviewing all the clinical, and biological data recorded (excepted the results of flow cytometry), in order to adjudicate between bacterial, viral or no infection, and among infected patients to classify into infection, sepsis or septic shock (sepsis 3.0).

After completing the recruitement of participants, a panel of cell surface markers will be measured by batch on a spectral cytometer, comprising notably the biomarkers of interest already published : HLA-DR, CD169 and CX3CR1 on monocytes, and MerTk, CD64 and CD24 on neutrophils.

The performances of the combinations of cell surface markers already identified in the littérature will be tested prioritarily. However, in order to refine the best combinations of biomarkers to discriminate bacterial from viral infection, machine learning algorithms like gradient boosting tree and support vector machine tools will be applied on the entire results of cell surface markers measured. The diagnostic performance will be evaluated calculating the sensitivity, specificity, area under the ROC curve of the biomarkers combinations selected.

• Study Type: Observational
• Enrollment (Estimated): 500

Contacts and Locations

• Study Contact: Name: laetitia Velly, MD; Phone Number: (33)7 82 28 94 91; Email: laetitia.velly@aphp.fr
• Study Contact Backup: Name: Pierre Hausfater, MD, PhD; Phone Number: (33)6 85 01 30 15; Email: pierre.hausfater@aphp.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Patients admitted to the ER with a suspicion of infection

Description

Inclusion Criteria:

• >18 year-old
• Attending one of the participant ED from Monday to Friday between 8:30 am to 3:00 pm
• With a suspicion of infection (defined by either a measured temperature above 38°C or any microbiology diagnostic test ordered during the routine care)
• Having blood sampling during routine care
• Informed and having expressed his/her non-opposition to participate

Exclusion Criteria:

• - Pregnancy
• No social insurance
• Prisoners

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
performances of cell surface markers combinations for diagnosis	area under the ROC curve of the different combinations of cell surface biomarkers for the diagnosis of bacterial or viral infection.	through study completion, an average of 9 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
performances of cell surface markers combinations for severity assesment	area under the ROC curve of the different combinations of cell surface biomarkers for the diagnosis of infetion, sepsis or septic shock	through study completion, an average of 9 months
performances of cell surface markers combinations according to the age range of participants	area under the ROC curve of the different combinations of cell surface biomarkers in the subgroups 18 to 75 year-old and >75 year-old for the diagnosis and severity assesment	through study completion, an average of 9 months

Collaborators and Investigators

• Sponsor: Assistance Publique - Hôpitaux de Paris

Study record dates

Study Major Dates

• Study Start (Estimated): March 1, 2024
• Primary Completion (Estimated): November 1, 2024
• Study Completion (Estimated): December 1, 2024

Study Registration Dates

• First Submitted: November 13, 2023
• First Submitted That Met QC Criteria: November 30, 2023
• First Posted (Actual): December 4, 2023

Study Record Updates

• Last Update Posted (Estimated): December 21, 2023
• Last Update Submitted That Met QC Criteria: December 20, 2023
• Last Verified: December 1, 2023

More Information

Terms related to this study

• Keywords: Flow cytometry; Bacterial infection; HLA-DR; CD24; Viral infection; CD64; MerTk; CX3CR1; CD169
• Additional Relevant MeSH Terms: Pathologic Processes; Disease Attributes; Emergencies; Infections; Communicable Diseases; Virus Diseases
• Other Study ID Numbers: APHP231707

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES

IPD Plan Description

The procedures carried out with the French data privacy authority (CNIL, Commission nationale de l'informatique et des libertés) do not provide for the transmission of the database, nor do the information and consent documents signed by the patients.

Consultation by the editorial board or interested researchers of individual participant data that underlie the results reported in the article after deidentification may nevertheless be considered, subject to prior determination of the terms and conditions of such consultation and in respect for compliance with the applicable regulations

• IPD Sharing Time Frame: Beginning 3 months and ending 3 years following article publication. Requests out of these time frame can also be submitted to the sponsor
• IPD Sharing Access Criteria: Researchers who provide a methodologically sound proposal.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No